JP4478115B2 - Method for forming conductive circuit - Google Patents

Description

  The present invention relates to a method of forming a conductive circuit by electroless plating on the surface of a substrate on which a cycloolefin-based resin is injection-molded, and in particular, in the electroless plating step, imparting polarity (also referred to as wetting). The present invention relates to a method for forming a conductive circuit that is not required.

  A method of forming a predetermined circuit pattern made of a layer of a conductive material such as copper on the surface of a base made of an insulating resin by electroless plating in order to form an electric circuit used for an electronic device such as a cellular phone. Various proposals have been made. In one of these methods, a predetermined layer consisting of a conductive material layer is formed by electroless plating on the surface of a substrate on which a cycloolefin resin having a low dielectric loss tangent to a high frequency signal and excellent chemical resistance is injection molded. There is a method of forming a circuit pattern (see, for example, Patent Document 1).

  A method of forming a predetermined circuit pattern made of this conductive material layer is as follows. That is, first, a cycloolefin resin, which is an amorphous resin containing a soft polymer such as a rubber elastic body, is injection-molded to form a substrate. Next, a thermoplastic polyester resin is injection-molded on the surface of the substrate to mask a portion where a conductive circuit is to be formed. Then, the masked substrate is immersed in an etching solution to roughen the surfaces of the substrate containing the soft polymer such as a rubber elastic body and the masking material, and on the roughened substrate and the masking material. The catalyst used as the catalyst nucleus of electroless plating is provided. Although the cycloolefin resin itself has etching resistance, since the soft polymerization of the rubber elastic body and the like contained in the cycloolefin resin is dissolved by the etching solution, the surface of the substrate not covered with masking is also present. Roughened.

Next, when the masking material covering the surface of the substrate is removed, the surface of the substrate is roughened and a portion where a conductive circuit to which a catalyst is applied is to be formed is formed. When immersed in an electroless plating solution, a conductive circuit can be formed in a portion where the conductive circuit is to be formed. In addition, since the surface roughening required for electroless plating and catalyst provision are not made | formed in the part which removed the masking material, a plating layer is not formed but the insulation of an electroconductive circuit is ensured.
JP 2003-115645 A (pages 1 to 7)

  The means described in Patent Document 1 uses a cycloolefin resin having a low dielectric loss tangent to a high-frequency signal and having chemical resistance, heat resistance, water resistance, etc. as a substrate for forming a conductive circuit. Thus, a circuit board having a low dielectric loss in a high frequency region and excellent in durability is provided. However, this means had many improvements. That is, firstly, in the above-described means, a mask made of a thermoplastic resin is also roughened by etching and given a catalyst, so that an electroless plating layer is also formed on this mask. Therefore, in order to selectively form the electroless plating layer only on the portion where the conductive circuit is to be formed on the substrate, it is necessary to remove the mask before or after the electroless plating. Therefore, a process and equipment for removing the mask are required, and the cost and manufacturing time increase accordingly.

  Second, as a means for forming a conductive circuit on an insulating substrate, electroless plating is selectively performed only on a portion of the surface of the plating substrate that is not covered with a mask, as in the above-described means. On the contrary, there is a means for forming a plated layer to be plated on a non-platable substrate and selectively performing electroless plating only on the plated layer. However, in the latter means, the layer to be plated remains as it is below the conductive circuit formed by electroless plating or the like. Therefore, in the configuration in which the layer to be plated is left on the substrate in this manner, the layer to be plated also has a low dielectric loss tangent to a high frequency signal, and has chemical resistance, heat resistance, water resistance, etc. It is desirable to have. Moreover, it is desirable to further improve the compatibility between the layer to be plated and the substrate and further strengthen the adhesion between them.

  Fourthly, in order to impart a catalyst that is usually the core of electroless plating, the imparted surface of the catalyst must have a polar group (hydrophilicity) that attracts catalyst ions. A (wetting) step is required. Here, if the polarity imparting (wetting) step can be omitted, the cost and the manufacturing time can be reduced accordingly. Fifth, the electroless plating is the formation of a plating layer of a single metal such as so-called copper, nickel, or gold, and cannot form an alloy plating layer. Therefore, the durability with respect to the contact pressure of a switch or the like is insufficient only by electroless plating, and it becomes difficult to weld a contact for a connector to this conductive circuit.

  Accordingly, an object of the present invention is to provide a method for forming a conductive circuit that can solve the above-described problems. Specifically, first, there is no need to remove the mask formed on the substrate. Secondly, both the substrate and the mask have a low dielectric loss tangent to a high-frequency signal and have chemical resistance, heat resistance, water resistance, and the like. Thirdly, the compatibility between the mask material and the substrate is further improved, and the adhesion between them is further strengthened. Fourthly, the polarity imparting (wetting) step for imparting a catalyst for electroless plating is omitted. And fifth, there is to form a conductive circuit with improved durability and weldability.

  As a result of extensive research, the inventor of the present application uses a cycloolefin-based resin for both the base and the mask that selectively covers the surface of the base, and by mixing the soft polymer only in one of the two, It has been found that the above-mentioned problems can be solved at once.

  That is, the cycloolefin resin is a cycloolefin copolymer resin in which a linear olefin is copolymerized with a cycloolefin resin and a cycloolefin resin, both of which have a low dielectric loss tangent to a high frequency signal as described above, and Since it has chemical resistance, heat resistance, water resistance, etc., it can be used not only for the substrate but also for both the substrate and masking, compared to using a cycloolefin resin only for the substrate. A circuit board having a low dielectric loss in a high frequency region and excellent durability can be formed. Moreover, by using the same resin material for both the base and the masking, the compatibility of both is further improved, and the adhesion between the two can be further strengthened.

  Next, since the cycloolefin resin itself has excellent etching resistance, it is not roughened by chemical etching and does not have a polar group (hydrophilicity) that attracts catalyst ions. For this reason, the catalyst is not adsorbed on the surface. On the other hand, the cycloolefin resin mixed with a soft polymer can be roughened easily by dissolving the soft polymer by chemical etching. Furthermore, since the roughened surface itself has a polar group (hydrophilicity) that attracts catalyst ions, it is not necessary to provide a step of imparting polarity (wetting) before applying the catalyst. Therefore, it is possible to easily form a conductive circuit by electroless plating only in the cycloolefin resin portion mixed with the soft polymer by an extremely simple process.

  That is, the first feature of the method for forming a conductive circuit according to the present invention is that a first step of forming a primary substrate by injection molding a cycloolefin resin mixed with a soft polymer, and a phase corresponding to the primary substrate. Using a cycloolefin resin that is not mixed with a soluble soft polymer, a masking layer that covers the surface of the primary substrate except for a portion where a conductive layer having a predetermined circuit pattern is to be formed is injection-molded. And a second step of forming a next substrate. Further, a third step of roughening a portion where the conductive layer not covered with the masking layer is to be formed, and a fourth step of forming a conductive layer by electroless plating on the portion where the roughened conductive layer is to be formed. Process. In the fourth step, the polarity imparting (wetting) step is omitted.

  Contrary to the means described above, a primary substrate is formed from a cycloolefin resin not mixed with a soft polymer, and a cycloolefin resin mixed with a soft polymer is injection-molded on the surface of the substrate to be plated. If a layer is formed, an electroless plating layer can be selectively formed only on the surface of the layer to be plated, and characteristics equivalent to those described above can be provided. Therefore, the second feature of the method for forming a conductive circuit according to the present invention is that a first step of forming a primary substrate by injection molding a cycloolefin resin not mixed with a soft polymer, and a phase with respect to the primary substrate. Using a cycloolefin resin mixed with a soluble soft polymer, a layer to be plated is injection-molded on the surface of the primary substrate where a conductive layer having a predetermined circuit pattern is to be formed, And a second step of forming a secondary substrate. Further, a third step of roughening the surface of the layer to be plated and a fourth step of forming a conductive layer on the roughened surface of the layer to be plated by electroless plating are provided. In the fourth step, the polarity imparting (wetting) step is omitted.

  The primary substrate has a through hole, and it is desirable that a part of the layer to be plated is injection-molded on both the one surface and the other surface of the primary substrate through the through hole. By configuring in this way, for example, when both the front and back surfaces of the primary substrate are covered with the layer to be plated, it is sufficient to fill the mold with the cycloolefin resin from one surface side of the primary substrate. It is possible to simplify the shape of the mold.

  In addition, after the fourth step of forming the conductive layer, a fifth step of laminating electroplating on the conductive layer, and a nonconductive precipitation residue remaining on the surface of the cycloolefin resin not mixed with the soft polymer It is desirable to comprise the 6th process of removing by chemical dissolution. That is, by electroplating on the electroless plating layer, for example, thick alloy plating can be quickly laminated and formed, so that a conductive layer circuit excellent in durability and weldability can be formed. Further, if a part of the catalyst or plating other than the surface of the cycloolefin-based resin not mixed with the soft polymer, that is, the portion where the conductive layer is to be formed remains, there is a risk of causing insulation failure or the like. Therefore, it is desirable to remove these residues by chemical dissolution or the like. For example, when electrolytic copper plating is laminated on a conductive layer made of electroless copper plating, a conductive layer is formed when the residue is chemically dissolved. In some cases, the electrolytic plating layer to be damaged may also be impaired. However, when electrolytic gold plating is laminated, the copper and nickel residues of the underlying plating can be dissolved and removed with nitric acid, while this gold plating cannot be dissolved with nitric acid, so unnecessary residues can be selectively dissolved and removed. Can do.

  Therefore, in the present invention, these residues are removed by chemical dissolution, and electroplating is performed on the electroless plating layer, thereby providing a marginal thickness against erosion by this chemical dissolution.

  Furthermore, the cycloolefin resin is preferably a cycloolefin copolymer resin composed of a cycloolefin resin and a linear olefin. Since the cycloolefin copolymer resin which does not mix a soft polymer is a transparent body, light is easily transmitted. Therefore, for example, when a cycloolefin copolymer resin not mixed with a soft polymer is used for the primary substrate, a conductive circuit having multiple functions such as illumination, light guide, and optical functions such as a lens can be formed.

  Here, the “soft polymer” means a material that dissolves in the etching solution, such as natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, thiocol rubber, acrylic rubber, urethane rubber, silicone rubber, epichloroform. Hydrin rubber, styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS) ), Styrene-isoprene block copolymer, hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), or ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), ethylene-butene copolymer, ethylene-octene copolymer, olefin rubber such as linear low density polyethylene elastomer, or Butadiene-acrylonitrile-styrene-core shell rubber (ABS), methyl methacrylate-butadiene-styrene-core shell rubber (MBS), methyl methacrylate-butyl acrylate-styrene-core shell rubber (MAS), octyl acrylate-butadiene-styrene-core shell rubber (MABS) ), Alkyl acrylate-butadiene-acrylonitrile-styrene-core shell rubber (AABS), butadiene-styrene-core shell rubber, methyl methacrylate-butyla Relate - core shell type particulate elastic body siloxane-containing core shell rubber such as siloxane, or rubber obtained by modifying them corresponds.

  “Cycloolefin resin” means, for example, an addition polymer of a cycloolefin monomer and ethylene, an addition polymer of a cycloolefin monomer, a ring-opening polymer of a cycloolefin monomer, and a hydride thereof. , Hydrogenated aromatic ring portion of polymer of aromatic vinyl monomer, hydrogenated aromatic ring portion of random or block copolymer of aromatic vinyl monomer and conjugated diene monomer, And amorphous resins such as polymers of alicyclic vinyl monomers. Here, the cycloolefin monomer is a cycloolefin obtained by addition reaction of cyclopentadiene and olefin, dicyclopentadiene, and polycyclic unsaturated hydrocarbons such as tetracyclododecene, and alkyls thereof. It means a polycyclic unsaturated hydrocarbon derivative which is a polar group substituent such as a substituent, a carboxyl group, an acid anhydride group, an epoxy group, an amide group, and an ester group.

  The “primary substrate” means a part or a part of the part on which a “masking layer” or a “plating layer” to be described later can be injection-molded. Moreover, not only a planar thing but what forms a three-dimensional circuit is also included. The “predetermined circuit pattern” means a portion where a conductive circuit is to be formed by electroless plating described later, and includes not only a two-dimensional pattern but also a three-dimensional pattern. Moreover, the case where it provides in the surface of the internal space opened on the surface of a primary base | substrate is also included. “Conductive layer” means a metal layer formed by electroless plating described later.

  The “masking layer” means a coating layer on the surface of the primary substrate that covers a portion excluding a predetermined portion, and finally each conductive circuit formed on the surface of the primary substrate is It means those that are electrically insulated from each other. The “secondary substrate” means the whole including both the primary substrate and a “masking layer” injection-molded on the surface of the primary substrate or a “layer to be plated” described later. “Roughening” refers to mixing and dispersing in the surface of the primary substrate or the layer to be plated when the primary substrate or the layer to be plated, which has been injection molded by mixing the “soft polymer” described above, is immersed in an etching solution. This means that the “soft polymer” is selectively dissolved and the surface roughness is increased by the dissolved and removed missing portions.

  “Electroless plating” is a well-known technique in which electrons are released by the oxidative decomposition of the reducing agent in the plating solution, and the dissolved metal in the plating solution is deposited on the surface to be plated by the reducing action of the free electrons. As the metal that forms the conductive layer by electroless plating, copper, nickel, cobalt, tin, and the like are applicable. “Polarization” (wetting) ”means that, as described above, a polar group (hydrophilicity) that attracts catalyst ions with a surfactant or the like is provided on the surface to which the catalyst is applied.

  “Electrolytic plating” is a known technique, which means that a target metal is deposited on a surface to be plated by passing an electric current through an electrolytic solution containing metal ions. In the present invention, an electroless plating layer is used. And the target metal is deposited on the electroless plating layer. In addition, as a metal for electrolytic plating, copper, nickel, chromium, tin, gold | metal | money, silver, platinum, indium, or an alloy containing these corresponds, for example. “Non-conductive deposit” means a metal deposited by catalyst or electroless plating, for example, initial copper plating (non-continuous film).

  “Cycloolefin resin” means a polymer having an alicyclic structure in the main chain synthesized using cycloolefins as monomers, and examples of chemical structural formulas thereof are shown in FIGS. Specifically, those having the chemical structural formula shown in FIG. 3 include “ZEONEX (registered trademark)” manufactured by Zeon Corporation, “ZEONOR (registered trademark)” manufactured by the same company, and “ARTON” manufactured by JSR Corporation. Etc. ”. Moreover, the copolymer of a cycloolefin type monomer and a linear olefin corresponds to “Topas” manufactured by Ticona, “Appel” manufactured by Mitsui Chemicals, etc. as having the chemical structural formula shown in FIG. .

  First, by omitting the step of removing the mask formed on the substrate, the cost and circuit formation time can be reduced accordingly. Secondly, by using a cycloolefin resin for both the base and the mask, the dielectric loss tangent can be further reduced with respect to the high-frequency signal, and chemical resistance, heat resistance, water resistance, etc. can be achieved. . Thirdly, the compatibility between the mask material and the substrate can be further improved, and the adhesion between them can be further strengthened. Fourthly, by omitting the polarity imparting (wetting) step for imparting the electroless plating catalyst, the cost and the production time can be reduced accordingly.

  Fifth, by laminating electroplating on electroless plating, a conductive circuit with improved durability and weldability can be formed. Furthermore, by this electrolytic plating lamination, it is possible to remove residues such as catalyst remaining other than the portion where the conductive layer is to be formed by using chemical dissolution while preventing excessive erosion to the conductive layer. Further, by providing a through hole in the primary substrate, the mold shape can be simplified. Furthermore, for example, by using a cycloolefin copolymer resin in which a soft polymer is not mixed in the primary substrate, a multifunction product having an optical function can be formed.

  An embodiment of a method for forming a conductive circuit according to the present invention will be described with reference to FIG. First, as shown in FIG. 1A, a cycloolefin copolymer resin composed of a cycloolefin cyclic resin and a linear olefin, which is a cycloolefin resin 1, is added to a styrene-ethylene-polymer 1 as a soft polymer. A block-shaped primary substrate 1 is formed by injection molding a material obtained by mixing and diffusing 20% by weight of a propylene-styrene block copolymer elastomer (hereinafter referred to as “SESP”). Next, after washing and degreasing the primary substrate 1, removing dirt and oil components and drying, a soft polymer having compatibility with the primary substrate 1 is obtained as shown in FIG. Using a cycloolefin copolymer resin composed of a non-mixed cycloolefin resin and a linear olefin, a masking layer covering the surface of the primary substrate and covering a portion 1b other than the portion 1a on which a conductive layer having a predetermined circuit pattern is to be formed 2 is injection molded to form the secondary substrate 3.

Next, the secondary substrate 3 is washed and degreased (C), dried and dipped in an etching solution, and as shown in FIG. 1D, a conductive layer not covered with the masking layer 2 of the primary substrate 1 For the portion 1a to be formed, the mixed and dispersed SEPS is dissolved, and the surface of this portion is roughened. In addition, since the masking layer 2 itself has etching resistance, it is not roughened even when immersed in an etching solution, and maintains hydrophobicity. Here, as the etching solution, for example, a mixed acid solution of 400 g / liter of chromic anhydride and 200 ml / liter of sulfuric acid is used and immersed for 60 minutes at a temperature of 75 ° C.

  Next, the secondary substrate 3 is neutralized with an alkaline aqueous solution (E), washed and dried, then immersed in a catalyst-providing solution, and a conductive layer in which palladium chloride is not covered with the masking layer 2 of the primary substrate 1 is formed. Adsorb to the portion 1a to be formed (F). In addition, since the part 1a which should form the conductive layer which is not covered with the masking layer 2 of the primary base | substrate 1 is roughened by the etching liquid in the process (D) mentioned above, and polarity is provided (wet). Palladium chloride is easily and strongly adsorbed. On the other hand, as described above, the masking layer 2 itself is not roughened by the etching solution and is hydrophobic, so that palladium chloride does not adsorb. Therefore, palladium chloride is selectively adsorbed only on the portion 1a where the conductive layer is to be formed. Next, using the activation treatment agent, the adsorbed palladium chloride is reduced to form a catalyst nucleus made of metallic palladium (G).

  Next, the secondary substrate 3 is washed with water and immersed in an electroless copper plating solution, and a conductive layer 4 made of electroless copper plating is selectively formed on the surface of the primary substrate 1 (H). In addition, what is necessary is just to use the general thing applicable to a plastic material as an electroless copper plating solution, for example, 5-15 g / liter of copper sulfate is used as a metal salt, and 8 volume of a 37 volume% solution of formalin is used as a reducing agent. A solution having a temperature of 20 ° C. mixed with 12 ml / liter, 20-25 g / liter of Rochelle salt as a complexing agent, and 5-12 g / liter of sodium hydroxide as an alkaline agent can be used. The conductive layer 4 made of electroless copper plating is formed only on the surface 1a of the primary substrate 1 that is not covered with the masking layer 2 and on which the conductive layer to be roughened and provided with catalyst nuclei is to be formed. Is not formed in this masking layer, which has not been roughened and provided with catalyst nuclei. Therefore, the conductive layer 4 is selectively formed only on the portion 1a on the surface of the primary substrate 1 where the conductive layer having a predetermined circuit pattern is to be formed.

  Next, the electroless copper plating solution is removed by washing with water, and the electrolytic layer 4 is laminated on the surface using the conductive layer 4 as a cathode (I). In addition, what is necessary is just to use a general thing for electrolytic copper plating, and you may form electrolytic nickel plating, an electrolytic gold plating layer, etc. on this electrolytic copper plating 5 as needed.

  By the way, if a part of the catalyst or plating remains on the surface of the masking layer 2, there is a risk of causing an insulation failure. Therefore, the secondary substrate 3 after the electrolytic copper plating 5 (I) is chemically dissolved with a nitric acid solution or the like to remove a part of these remaining catalyst and plating (J). Here, if the thickness of the electrolytic copper plating 5 laminated on the electroless copper plating 4 is increased to some extent, even if the final finish is copper, there is a marginal thickness against this erosion due to chemical dissolution. The function of the circuit is not impaired. Further, by performing gold plating on the electrolytic copper plating 5, it is possible to prevent erosion due to this chemical dissolution. Finally, the nitric acid solution and the like are neutralized with an aqueous alkaline solution (K).

  Next, another embodiment will be described with reference to FIG. In this embodiment, the materials used for the primary substrate 1 and the masking layer 2 described above are reversed. Further, for the sake of convenience, the parts and parts corresponding to the parts and parts shown in FIG. 1 are numbered by adding 10 to the part numbers shown in FIG. Now, as shown in FIG. 2 (A), a cycloolefin copolymer resin composed of a cycloolefin resin and a linear olefin, which is one of the cycloolefin resins not mixed with a soft polymer, is injection-molded to form a block. A primary substrate 11 is formed.

  Next, the primary substrate 11 is washed and degreased to remove dirt and oil components and dried. As shown in FIG. 2B, a soft polymer having compatibility with the primary substrate 11 is obtained. Using the mixed cycloolefin resin and cycloolefin copolymer resin composed of linear olefin, the layer 12 to be plated is formed on the surface of the primary substrate where a conductive layer having a predetermined circuit pattern is to be formed. The secondary substrate 13 is formed by injection molding. Here, the soft polymer mixes and diffuses 20% by weight of SESP in the same manner as described above.

  Next, the secondary substrate 13 is washed and degreased (C), dried and dipped in an etching solution. As shown in FIG. 2D, the surface 12a of the layer 12 to be plated is mixed and dispersed. And the surface of this part is roughened. Note that the portion 11b that is the surface of the primary substrate 11 and is not covered with the layer 12 to be plated has etching resistance, so that it is not roughened even when immersed in an etching solution and maintains hydrophobicity. Here, the same etchant as described above is used.

  Next, the secondary substrate 13 is neutralized with an aqueous alkaline solution (E), washed and dried, and then immersed in a catalyst-providing solution to adsorb palladium chloride on the plated layer 12 (F). In addition, since the surface 12a of the to-be-plated layer 12 is roughened by the etching solution and imparted with polarity (wet) in the step (D), palladium chloride is easily and firmly adsorbed. On the other hand, as described above, the primary substrate 11 itself is not roughened by the etching solution and is hydrophobic, so that palladium chloride does not adsorb. Therefore, palladium chloride is selectively adsorbed only on the layer to be plated 12 which is a portion where the conductive layer is to be formed. Next, using the activation treatment agent, the adsorbed palladium chloride is reduced to form a catalyst nucleus made of metallic palladium (G).

  Next, the secondary substrate 13 is washed with water and immersed in an electroless copper plating solution to form a conductive layer 14 made of electroless copper plating on the surface 12a of the layer to be plated 12 (H). The electroless copper plating solution is the same as described above. The electroconductive layer 14 made of electroless copper plating is formed only on the surface 12a of the layer 12 to be plated which has been roughened and provided with catalyst nuclei, while the surface of the primary substrate 11 which has not been provided with roughening and catalyst nuclei. It is not formed on the surface 11b. Therefore, the conductive layer 14 is selectively formed only on the surface 12a of the layer 12 to be plated having a predetermined circuit pattern on the surface of the primary substrate 11.

  Next, the electroless copper plating solution is removed by washing with water, and the electrolytic layer 14 is laminated on the surface using the conductive layer 14 as a cathode (I). In addition, what is necessary is just to use a general thing for electrolytic copper plating, Furthermore, electrolytic nickel plating, an electrolytic gold plating layer, etc. may be formed on the electrolytic copper plating 15 as needed.

  Next, the secondary substrate 13 after the electrolytic copper plating 15 (I) is chemically dissolved with a nitric acid solution or the like, and the remaining catalyst and part of the plating are removed (J). Here, if the thickness of the electrolytic copper plating 15 laminated on the electroless copper plating 14 is increased to some extent, even if the final finish is copper, there is a marginal thickness against erosion by this etching. The function of is not impaired. Further, by performing gold plating on the electrolytic copper plating 15, it is possible to prevent erosion due to this chemical dissolution. Finally, the nitric acid solution and the like are neutralized with an aqueous alkaline solution (K).

  The cycloolefin resin used for the primary bases 1 and 11 and the masking layer 2 and the plated layer 12 described above includes glass fiber, titanium for the primary bases 1 and 11 and the masking layer 2 and the plated layer 12. By mixing a filler such as acid barium whisker, the change in dielectric constant, strength, durability, and the like can be improved. Furthermore, additives such as anti-blocking agents, antioxidants, nucleating agents, antistatic agents, process oils, plasticizers, mold release agents, compatibilizers, flame retardants, flame retardant aids, or pigments are mixed with these. Thus, the functional effects of the respective additives can be exhibited.

  As a cycloolefin resin mixed with a soft polymer, “ZEONEX # RS820 manufactured by Nippon Zeon Co., Ltd., Tg: about 140 ° C., hydrogenation rate: 99.7% or more, metal element amount: 1 ppm or less” in 100 parts In contrast, a styrene-ethylene-propylene-styrene block copolymer elastomer “Kuraray Co., Ltd. Septon number average molecular weight: 60000, Tg: at least one point at 40 ° C. or less, metal element amount: 15 ppm”, 30 parts, and 0.5 parts of phenolic antioxidant was added to obtain thermoplastic composition pellets. The pellet was injection molded at a resin temperature of 280 ° C. to form a block-shaped primary substrate.

  Next, after cleaning and degreasing the primary substrate, removing dirt and oil components and drying, using the above cycloolefin-based resin “ZEONEX # 480 manufactured by Nippon Zeon Co., Ltd.” not mixed with a soft polymer, A secondary substrate was formed by injection molding a masking layer covering the surface of the primary substrate except for a portion where a conductive layer having a predetermined circuit pattern was to be formed. The secondary substrate was washed and degreased and dried, and then immersed in an etching solution to roughen the surface of the primary substrate not covered with the masking layer. As this etching solution, a mixed solution of 400 g / liter of chromic anhydride and 200 ml / liter of sulfuric acid was used, and immersed at a temperature of 75 ° C. for 60 minutes. As a result, only the surface of the primary substrate not covered with the masking layer was roughened and wetted, and the masking layer was not roughened or wetted.

  Next, the secondary substrate was neutralized and washed and dried. In addition, "Neutlyzer PM50 manufactured by Shipley Far East Co., Ltd." was used as this neutralizing agent, and immersed for 3 to 5 minutes at a temperature of 50 ° C. Next, the secondary substrate was immersed in a catalyst-providing solution to adsorb palladium chloride on the surface of the primary substrate that was not covered with the masking layer. For this catalyst application, “Catapo Jet 44 manufactured by Shipley Far East Co., Ltd.” was used and immersed at a temperature of 50 ° C. for 8 to 10 minutes. As a result, it was confirmed that palladium chloride was adsorbed on the surface of the rough primary substrate which was not covered with the masking layer without further wetting. It was also confirmed that it was not adsorbed by the masking layer. The adsorbed palladium chloride was activated to form a catalyst nucleus made of palladium metal. In this activation, “Accelerator 19 manufactured by Shipley Far East Co., Ltd.” was used and immersed for 10 to 12 minutes at room temperature.

  Next, the secondary substrate is washed with water and immersed in an electroless copper plating solution, and a 0.05 to 0.3 μm thick conductive layer made of electroless copper plating is selectively formed on the surface of the primary substrate on which catalyst nuclei are formed. Formed. As an electroless copper plating solution, “Copper mix # 328L: 12.5%, # 238A: 12.5%, and # 328C: 2.5% manufactured by Shipley Far East Co., Ltd.” The solution mixed at 72.5% was immersed for 15 minutes at room temperature. From the above, it was confirmed that a conductive circuit by electroless copper plating can be selectively formed only on the surface of the roughened / catalyzed primary substrate not covered with the masking layer.

  As a cycloolefin copolymer resin composed of a cycloolefin resin and a linear olefin mixed with a soft polymer, "TOPAS # RSC10001 manufactured by Polyplastics Co., Ltd." Formed. Next, dirt and dust on the surface of the primary substrate are degreased and removed, and as a cycloolefin resin compatible with the primary substrate and not mixed with a soft polymer, “ZEONOR # 1020R manufactured by Nippon Zeon Co., Ltd.” Is used to form a secondary substrate by injection molding a masking layer covering the surface of the primary substrate except for the portion where the conductive layer having a predetermined circuit pattern is to be formed.

  Next, the secondary substrate was washed and degreased and dried, and then immersed in an etching solution comprising a mixed acid solution of chromic acid-sulfuric acid to roughen the surface of the primary substrate not covered with the masking layer. Next, neutralize and remove the chromic acid adhering to the secondary substrate with a hydrochloric acid solution, and deposit palladium chloride on the surface of the roughened primary substrate in the same manner as described above, and then reduce the palladium chloride. Thus, a catalyst nucleus made of palladium metal was formed. Next, standard electroless copper plating on ABS resin was performed on the secondary substrate. As a result, a conductive layer made of electroless copper plating is formed only on the surface of the primary substrate that is not covered with the masking layer and is roughened and provided with a catalyst. It was confirmed that no electrolytic copper plating was formed.

  Contrary to Example 2, a primary substrate was injection molded using “ZEONOR # 1020R manufactured by Nippon Zeon Co., Ltd.” as a cycloolefin resin not mixed with a soft polymer, and then compatible with the primary substrate. As a cycloolefin copolymer resin composed of a cycloolefin resin mixed with a soft polymer and a linear olefin, “TOPAS # RSC10001 manufactured by Polyplastics Co., Ltd.” is used. A layer to be plated was injection molded at a portion where a conductive layer was to be formed to form a secondary substrate.

  Subsequently, the secondary substrate was immersed in an etching solution, a catalyst applying solution, and an electroless plating solution in the same procedure as described above. As a result, only the layer to be plated is roughened and a catalyst is applied, and the surface of the primary substrate that is not covered with the layer to be plated is not roughened and no catalyst is applied. It was confirmed that the electrolytic plating layer can be selectively formed.

  In the same manner as in Example 3 described above, an electroless plating layer was selectively formed on the plated layer that was injection-molded on the surface of the primary substrate. Then, the electroless plating solution was washed away with water, and the electroless plating layer was used as a cathode, and an electrolytic copper plating having a thickness of 5 to 10 μm was laminated on the surface. As a result, it was confirmed that the electrolytic copper plating can be quickly laminated only on the electroless plating layer by a commonly used electrolytic copper plating method.

  Next, after the electrolytic copper plating was laminated, the entire secondary substrate was chemically dissolved with a sulfuric acid solution. As a result, it was confirmed that the electrolytic copper plating had a sufficient thickness against the erosion due to this chemical dissolution, and the function of the conductive layer was not impaired. Therefore, if there is a possibility that a part of the catalyst or plating remains on the surface of the primary substrate that is not covered with the layer to be plated, remove these sufficiently without causing overetching of the electrolytic copper plating. Can do.

  The method for forming a conductive circuit according to the present invention does not require removal of a mask formed on a substrate, both the substrate and the mask have a low dielectric loss tangent to a high frequency signal, and the compatibility between the mask material and the substrate. In addition, since polarity imparting (wetting) for imparting a catalyst for electroless plating is unnecessary, it can be widely used in industries related to electronic devices and the like.

It is process drawing which shows the formation procedure of an electroconductive circuit. It is process drawing which shows the other formation procedure of an electroconductive circuit. It is a chemical structural formula showing a specific example of a cycloolefin-based resin. 2 is a chemical structural formula showing a specific example of a cycloolefin monomer and a linear olefin copolymer.

Explanation of symbols

1,11 Primary substrate 1a Part where conductive layer is to be formed 1b Except part where conductive layer is to be formed (part covered with masking layer)
12 Layer to be plated 2 Masking layer 3,13 Secondary substrate 4,14 Electroless plating (conductive layer)
5,15 Electrolytic copper plating

Claims (5)

A first step of forming a primary substrate by injection molding a cycloolefin-based resin mixed with a soft polymer;
Using a cycloolefin resin that is compatible with the primary substrate and does not mix a soft polymer, masking covers the surface of the primary substrate except for the portion where a conductive layer having a predetermined circuit pattern is to be formed. A second step of injection molding the layer to form a secondary substrate;
A third step of roughening a portion where a conductive layer not covered with the masking layer is to be formed;
A fourth step of forming a conductive layer by electroless plating on the portion where the roughened conductive layer is to be formed,
In the fourth step, a polarity imparting (wetting) step is omitted. A method for forming a conductive circuit, wherein: A first step of forming a primary substrate by injection molding a cycloolefin-based resin not mixed with a soft polymer;
Using a cycloolefin resin mixed with a soft polymer having compatibility with the primary substrate, the portion to be plated on the surface of the primary substrate where a conductive layer having a predetermined circuit pattern is to be formed is plated. A second step of injection molding the layer to form a secondary substrate;
A third step of roughening the surface of the plated layer;
A fourth step of forming a conductive layer on the surface of the roughened plating layer by electroless plating,
In the fourth step, a polarity imparting (wetting) step is omitted. A method for forming a conductive circuit, wherein: In Claim 2, the primary substrate has a through hole,
A part of the layer to be plated is injection-molded on both surfaces of one surface and the other surface of the primary substrate through the through hole. In any 1 of Claims 1-3, after the 4th process of forming the said conductive layer, the 5th process of laminating | stacking electroplating on this conductive layer,
A method for forming a conductive circuit, comprising: a sixth step of removing, by chemical dissolution, the metal deposited by the electroless plating remaining on the surface of the cycloolefin resin not mixed with the soft polymer. 5. The method for forming a conductive circuit according to claim 1, wherein the cycloolefin-based resin is a cycloolefin copolymer resin including a cycloolefin-based resin and a linear olefin.

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